From 10,000 meters up, the impact of humans on the Earth is clear. Cities spanning kilometers are connected by roadways stretching to the horizon. Crowding the spaces in between are fields that supply food and industrial feedstock to satisfy a variety of human hungers. These fields feed humanity. Through stewardship we maintain their productivity and thus sustain societies that extend around the globe; if these fields fall into ill health, or if we push them into sickness, we risk the fate of those same societies.

Humans have a long history of modifying the living systems they rely on. Forests in Europe and North America have been felled for timber and have regrown, while other large tracts of land around the world have been completely cleared for use in agriculture. The animals and plants we humans eat on a regular basis have been selected and bred over millennia to suit the human palate and digestive tract. All these crops and products are shipped and consumed globally to satisfy burgeoning demand.

Our technology and trade thereby support a previously unimaginable quality of life for a previously impossible number of people. Humanity has kept Malthus at bay through centuries of growth. Yet our increasing numbers impose a load that is now impacting nature's capacity to support human societies. This stress comes at a time when ever-larger numbers of humans demand more: more food, more clean water, more energy, more education, more entertainment, more more.

Increasing human demand raises the question of supply, and of the costs of meeting that supply. How we choose to spend or to conserve land, water, and air to meet our needs clearly impacts other organisms that also depend on these resources. Nature has intrinsic value for many people in the form of individual species, ecosystems, and wilderness; nature also constitutes critical infrastructure in the form of ecosystems that keep us alive. That infrastructure has quantifiable economic value. Consequently, nature, and the change we induce in it, is clearly interwoven with our economy. That is, the security and health of human societies depends explicitly upon the security and health of natural systems. Therefore, as economic security is now officially considered as part and parcel of national security strategy, it is time to expand our understanding of national security to include natural security.